NEW YORK (Reuters) - Renowned commodities investor Jim Rogers said on Thursday that he bought oil last week as crude prices collapsed to near four-year lows and that the world is running out of known oil reserves.

Rogers told the Reuters Investment Outlook Summit in New York that he also closed his bets against the U.S. stock market in October, and plans to use the dollar's rally as an opportunity to exit dollar-denominated assets.

Rogers, who spoke via a conference call from Miami, said he is the world's worst market timer and a horrible short-term trader, but a sharp sell-off in oil prices suggested a bottom.

"Oil collapsed last week. Whenever you've had that sort of selling climax throughout any period in history, you are usually well-rewarded to buy it. It may not be the final bottom, but a bottom, so I'm buying oil again," he said.

Rogers, who remains bullish on commodities, estimated known world oil reserves at today's consumption rate are about 16 years, which indicates crude prices will again trend higher.

"We're going to see $200 oil at some point, it may be by 2013. It's a sad fact but the world is running out of known oil," he said.

Many of Rogers's investments reflect a bearish view of the U.S. economy, which he said is poised to enter a period of stagnation, just as Japan suffered during its "lost decade" in the 1990s.

Rogers rose to fame in the investment world as co-founder with George Soros the Quantum Fund in 1970. The fund returned 4,200 percent over the next decade, compared with a 50 percent gain in the S&P 500 index.

"We have unbelievable mistakes every week coming out of Washington, just as Japan did in the 1990s, just as America did in the 1930s," he said. "This could turn into a gigantic mess."

Rogers attributed his grim outlook to worries about the size of the U.S. government's growing deficit and the unwillingness on the part of authorities to let banks fail. He said he expected the U.S. economy to be in bad shape for a considerable time.

"I am most worried about the United States and what's going on," said Rogers, who said he is proud to be American but he has serious doubts about the country's future.

Rogers also said he covered most of his bets that the U.S. stock market would decline in October, when "that too felt like a selling climax," he said.

He also said he plans to get out of U.S. securities he's owned for more than two decades if there is a rally soon.

"The market will probably rally for a while into January or March, and then we'll have more problems next year and perhaps into 2010," he said.

"I plan to get out of all of my U.S. dollars at some time throughout this rally. The dollar is a terribly flawed currency, and perhaps a doomed currency," he said.

Rogers said that he is investing on growth areas in China and Taiwan, such as shares in water treatment, tourism and agriculture.

He is bullish on Asia because the region has savers and thus creditor nations.

"This is where the money is, and throughout history the world has moved to where the money is," he said.

"To me it's incomprehensible that people would lend to the United States government for 30 years at 3 or 4 percent," he added.

Rogers sold his New York mansion in December and has been living in Singapore. He is long-term bull on China, where he first traveled on motorcycle in the early 1980s. He again traveled on motorcycle through China and six continents a decade later, a trip that formed his book "Investment Biker."